Purification of detergent alkylates

ABSTRACT

SUSPENDED ALUMINUM HALIDE CATALYST SLUDGE IS REMOVED FROM CRUDE DETERGENT ALKYLATE BY INTRODUCING A SMALL AMOUT OF WATER TO THE DETERGENT ALKYLATE IN ORDER TO COAGULATE THE SUSPENDED SLUDGE. THE COAGULATED SLUDGE IS THEN SEPARATED FROM THE DETERGENT ALKYLATE AND THE PURIFIED DETERGENT ALKYLATE IS WASHED WITH WATER OR ALKALINE SOLUTION TO REMOVE SUBSTANTIALLY ALL ACIDITY OR INORGANIC SALTS PRESENT IN THE PRODUCT.

Nov. 21, 1972 o. c. KERFooT ET AL 3,703,559

PURIFICATION OF DETERGENT ALKYLATES Filed Nov. 25, 1970 ATTORNEY United States Patent O 3,703,559 PURIFICATION OF DETERGENT ALKYLATES Oliver C. Kerfoot, Ponca City, Okla., and George W. Buchmann, Lake Charles, La., assignors to Continental Oil Company, Ponca City, Okla. Continuation-in-part of application Ser. No. 742,497, July 5, 1968. This application Nov. 25, 1970, Ser.

Int. Cl. C07c 7/00 U.S. 'Cl. 260-674 A 7 Claims ABSTRACT OF THE DISCLOSURE Suspended aluminum halide catalyst sludge is removed from crude detergent alkylate by introducing a small amount of water to the detergent alkylate in order to lcoagulate the suspended sludge. The co'agulate'd sludge is then separated fro-m the detergent alkylate and the purified detergent alkylate is washed with water or alkaline solution to remove substantially all acidity or inorganic salts present in the product.

CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of application Ser. No. 742,497, filed July 5, 1968, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention Description of the prior art It is well known to prepare highly effective, water'I soluble surfactants by sulfonating, either with oleum or sulfur trioxide, the detergent alkylates obtained by alkylating an excess of an aromatic compound, usually benzene, with an olefin having from about 8 to 18 carbon atoms. The art has become very advanced in the preparation of this type of surfactant, particularly with respect to techniques for obtaining relatively pure products approaching whiteness in color. While any moderate discoloration of alkyl benzene sulfonates has no discernible effect upon the surface active properties, nevertheless good color for these products has become a prime requirement on the part of the manufacturer or formulator of the detergent composition in which these surfactants are prevalently employed.

In the manufacture of detergent alkylates in accordance with the Friedel-Crafts reaction wherein an aluminum halide, such as aluminum chloride, is employed as the alkylation catalyst, a crude alkylate product is obtained containing an appreciable amount of suspended sludge. The exact nature of the sludge is not certain but is believed to be complexes of the type ArHztAiClf wherein Ar represents the aromatic hydrocarbon constituent. These complexes or impurities, while being relatively insoluble in the alkylation reaction mixture, cannot be completely separated and a minor amount remains in the alkylate regardless of the type of separation employed. While the amount of sludge remaining suspended in the alkylate is small, such as in the order of 0.7 percent or less, the presence of even this small amount of ice sludge adversely affects alkylate product quality. Further, if one employs any type of recycle stream of the alkylate product it is desirable that such product be substantially free of sludge.

The purification procedures generally utilized for removing the sludge from the alkylate product in order to prepare light-colored sulfonate salts of the aforedescribed surfaetants include time consuming mechanical sepanatory methods, such as filtration, prolonged settling, and the like, and expensive physical treatment methods, such as treating the crude alkylation reaction mixture with concentrated sulfuric acid prior to recovering a suitable fraction of the alkylate for conversion to its sulfonic acid derivatives. Thus, new and improved methods for removing the remaining sludge from the alkylate product are constantly being sought.

SUMMARY OF THE INVENTION The present invention resides in a purification method for obviating the presence of suspended sludge and thus certain sulfonate color precursors prone to be present in a detergent alkylate product prepared by an aluminum halide, such as aluminum chloride or aluminum bromide, catalyzed condensation of a partially chlorinated normal paraffin or olefin with an aryl compound, such as benzene. Specifically, this method involves introducing a small controlled amount of water to the crude detergent alkylate in order to coagulate the suspended sludge remaining in the reaction product mixture after the sludge settling step so that the suspended sludge can be removed prior to washing the product alkylate with water or dilute alkaline solution to remove any residual acidity or inorganic components prior to distillation of the alkylate. By contacting the reaction product mixture containing the suspended sludge with an amount of water sufficient to coagulate but not hydrolyze the sludge complex the coagulated sludge can readily be separated from the detergent alkylate thus providing a purified detergent alkylate.

OBJECTS OF THE INVENTION An object of this invention is to remove suspended aluminum halide catalyst sludge from crude detergent alkylate. Another object of this invention is to provide an economical, eliicient and simplified method for removing suspended sludge from detergent alkylates thereby obviating the presence of color bodies and sulfonate color precursors from n-alkaryls prepared using alkyl chlorides or olefins .as the alkylating agent prior to conversion thereof to sulfonic acid salt derivatives by means of a sulfonating agent.

These and other objects, advantages and features of the present invention will be apparent to those skilled in the art upon a reading of the following detailed description and drawing, in which:

The drawing is a schematic illustration of the production of detergent alkylate including the purification proceduce of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS The detergent alkylates purified by the present invention can be any detergent alkylates prepared wherein an aluminum halide, such as aluminum chloride or aluminum bromide, is employed as the alkylation catalyst in the preparation of detergent alkylates. In order to further illustrate the invention, the method for preparing detergent alkylates as set forth in U.S. Pat. No. 3,3 116,294 (1967) is hereby incorporated in part. The invention will now be explained with reference to the drawing wherein FIG. 1 depicts a process for the preparation of a purified detergent alkylate.

In the preparation of detergent alkylates a n-parafin having from about 8 to 18 carbon atoms is partially chlorinated so as to produce monochlorinated paraffins. Either conventional liquid or vapor phase chlorination of the paraffins can be employed. However, regardless of which of these chlorination techniques is employed, the degree of chlorination should be at least 10 mole percent and not over 35 mole percent.

The ratio of chlorine to paraffin to be chlorinated thereby can be varied over the range from about 1:3 to 1:10, respectively, on the mole basis. However, it is preferred to operate at a ratio of about 1:5 moles of chlorine to parafiin, respectively, from an economical standpoint because use of very low amounts of chlorine necessitates excessive recycling of the paraffin. After suitably chlorinating the paraffin mixture, the halogenated product is then purged of by-product HCl and unreacted chlorine. Purging can be readily accomplished through the use of an inert gas, such as, for example, nitrogen.

For vapor phase thermal chlorination, temperatures of 230-350 C. are operable. However, more important than temperature is the space velocity and residence time. In order to avoid uncontrolled combustion type reaction of chlorine and alkane, a linear velocity of at least about 88 feet per second is necessary. At this high velocity a residence time of about .5 to 1 second will give good conversion of reactants to products.

Liquid phase chlorination temperatures that can be used range from about room temperature to about 200 C. With photochemical or other catalysis, lower temperatures can be used and still obtain good reaction rates. It must be remembered that chlorination of an alkane is an exothermic reaction, consequently, when it is desired to conduct the reaction at any particular temperature, the reaction should be initiated at a temperature sufliciently below that ultimately desired in order to compensate for the increase in temperature which will result as consequence of the heat of reaction. The time for chlorination varies extensively and depends on the ratio of chlorine to parain used, temperature, etc. The time necessary to effect the desired degree of chlorination under any particular set of conditions can be readily determined experimentally. The chlorination product is then employed as the alkylatable component in the subsequent alkylation step.

Similarly, the detergent alkylates puried by the present invention can be any detergent alkylates prepared by the alkylation of an aromatic hydrocarbon, such as benzene, homologs of benzene, including toluene, ethyl benzene, xylene, ispropylbenzene, butylbenzene, etc.; cymene and its homologs and naphthalene and its homologs, with olens containing about to 18 carbon atoms, such as ethylene isobutylene, hexylene, octylene, dodecene, and the like where an aluminum halide such as aluminum chloride or aluminum bromide is employed as the alkylation catalyst. Such a process is set forth in U.S. Pat. No. 3,118,956 (1964), which is hereby incorporated in this application.

In the production of detergent alkylate an aryl hydrocarbon compound, a chlorination product or olefin compound, and a catalyst compound are introduced into alkylation reactor vessel 11 by conduit means 12, 13, and 14 respectively. Any suitable aluminum halide catalyst can be employed such as aluminum chloride or aluminum bromide with aluminum chloride being preferred. In addition, any suitable aryl compound such as toluene, xylene, naphthalene and the like can be employed with benzene being the preferred aryl compound.

The alkylation temperature Will vary, depending upon whether the alkylation agent is an alkyl halide or an olefin. When alkyl halides are employed as the alkylation agent, the temperature can be varied over wide limits ranging from about room temperature to 80 C. A preferred temperature range is in the order of from about 40- 50 C. However, when an olefin is employed as the 4 alkylation agent, the temperature ranges from about 5 to 35 C.

The ratio of aryl compound, specifically benzene, to the amount of alkyl halide or olefin alkylating agent can also be varied over wide limits. For example, such ratios can range from about 1 to 20 moles of the benzene to 1 mole of the alkyl chloride component of the alkylating stock. On the aforesaid basis, a preferred range of benzene to alkyl chloride ranges from about 5:1 to 10:1, respectively.

The amount of alkylating catalyst, specifically aluminum chloride, suitable for effecting alkylation can conveniently be based upon the Weight of the alkyl chloride or olefin content of the alkylating stock.

The alkylation reaction can be carried out in a continuous or batchwise manner. In either manner, effective contact time between the catalyzed reactants is in the order of from about 5 to 60 minutes. The precise time needed for effecting alkylation is obviously dependent upon a host of factors, including the amount of catalyst used, ratio of benzene to alkyl chloride or olefin employed, temperature, etc.

Upon completion of the alkylation reaction the effluent of same is withdrawn from alkylation reactor vessel 11, via conduit means 16 which is in fluid communication with separator means 17 wherein the majority of the aluminum halide catalyst sludge is removed from the alkylation reaction mixture. The suspended sludge is then withdrawn from separator means 17 via conduit means 18. However, after the separation of the major portion of the catalyst sludge from the crude detergent alkylate a small amount of the catalyst sludge, generally in the order of about 0.1 to 0.7 weight percent and more often in the range of 0.1 to 0.3 weight percent, remains suspended in the detergent alkylate which is removed from separator means 17 via conduit means 19. Conduit means 19 which is in fluid communication with separator means 17 is also in fluid communication with a coagulator means 21 so that the crude detergent alkylate containing the minor amount of suspended sludge is passed thereto. The presence of even this small amount of catalyst sludge, which consists mainly of complexes of the spent aluminum halide catalyst and aromatic hydrocarbon compounds, adversely affects the alkylate product quality in that the suspended sludge causes undesirable color in the sulfonation products of the detergent alkylate. Thus, it is to the removal of the suspended sludge in the detergent alkylate that the present invention is directed.

It is well known that it is undesirable to contact the detergent alkylates containing the suspended sludge with water because the water hydrolyzes the suspended sludge and thus releases the organic portion of the catalyst complex, which is known as sprung oil, into the crude detergent alkylate and this results in quality deterioration of the detergent alkylates. Thus, it was indeed surprising when we found that when water was added via conduit means 22 to the detergent alkylate containing suspended sludge in coagulator means 21 in an amount up to about 50 weight percent water based on the weight of the suspended sludge present in the detergent alkylate that the small amount of water used coagulated the suspended sludge so that when the effluent from coagulator means 21 was passed to a second separator means 23 via conduit means 24 the coagulated sludge component could be separated thereby enabling same to be readily removed from the detergent alkylate. Any suitable means such as settling, centrifuging, electrostatic precipitation and the like can be employed as second separator means 23. However, it was noted in experimentation that the coagulated sludge must be removed from the detergent alkylate in second separation zone 23 within a relatively short period of time, i.e. about 6 hours, via any suitable means such as conduit means 26 because the addition of even this minor amount of water causes the sludge to undergo a gradual hydrolysis and thus the organic portion of the catalyst complex would be released into the detergent alkylate. The temperature at which the crude detergent is maintained during the addition of the water can range from about to 95 C., preferably from about 25 to 60 C. However, less water is required to coagulate and precipitate the suspended catalyst sludge at higher temperatures than at the lower temperatures.

The water employed to coagulate fand precipitate the suspended sludge present in the detergent alkylate can be introduced into the detergent alkylate as dissolved and/or suspended water in a hydrocarbon carrier. Any suitable hydrocarbon carrier can be employed. However, preferably the hydrocarbon carrier is the same aryl compound, such as benzene, toluene, xylene, naphthalene, and the like, in the alkylation step in the production of the detergent alkylates.

The purified detergent alkylate, the efiiuent from second separation zone 23, is then passed via conduit means 27 to wash means 28 wherein water or an alkaline solution is employed to remove any residual acidity or inorganic salts present in the purified detergent alkylate. The water or alkaline solution is introduced into wash means 28 via any suitable means such as conduit means 29 and the spent wash liquid is withdrawn from wash means 28 via conduit means 31. The washed detergent alkylate is removed from wash means 28 via conduit means 32 and passed to a distillation means for separation of the desired components of the detergent alkylate. In order to illustrate the invention further, the following examples are set forth. However, the examples are given primarily for purposes of illustration; and, any enumeration of details contained therein shall not be construed as limitations upon the invention except as such are expressed in the appended claims.

EXAMPLE I A sample of crude detergent alkylate reaction product mixture obtained by the aluminum chloride catalyzed :alkylation of benzene with partially chlorinated C12-C14 n-paratiins and containing about 0.15 percent of suspended aluminum chloride catalyst sludge was treated with water in incremental portions at about C. When 0.06 weight percent of water had been added, the suspended sludge coagulated and settled out rapidly leaving a clear, nearwhite crude alkylate. Samples of the crude alkylate were drawn after l hour, 7 hours, and 30 hours standing over the settled sludge. U.V. iabsorbances on [a control untreated sample and the treated samples after neutralization and drying were as follows:

U.V. Settling absorbance time at 368 m. (hours) Control run i g: g l 0. 39 30 EXAMPLE II A sample of crude detergent alkylate identical to the orude detergent ialkylate employed in Example I, was heated in an open ask slowly to about 90 C. At about 70 C. a very noticeable coagulation of the suspended sludge began, followed by rapid settling. The separated detergent alkylate, after neutralization, showed an absorbance of 0.21 on U.V. at 368 m. The coagulation effect was produced by moisture pickup from the air rather than the heating itself. Thus, the example illustrates that at higher temperatures less water is required to precipitate the sludge.

The U.V. absorbance of the resulting neutralized detergent alkylates in Examples I and II is illustrative of the relative measures of the amount of sprung oil in the purified detergent alkylates. The decrease in the sludge in the detergent alkylates when the sludge is precipitated in accordance with this invention is about the same as with sulfuric acid washings, powdered attaplugus clay treatments, yand the like. However, by employing water one is not faced with expensive treating materials, high corrosion rates of equipment, and other uneconomical steps.

Having thus described the invention, we claim:

ll. In a method for the production of detergent alkylate by alkylating aryl hydrocarbons with chloroparaiins or oleins in the presence of an aluminum halide catalyst to produce a detergent alkylate portion containing small amounts of suspended catalyst sludge and a catalyst sludge portion containing a major portion of the catalyst sludge, separating said detergent alkylate portion from said catalyst sludge portion and thereafter washing said detergent alkylate portion with water or an alkaline solution to remove any residual acidity or inorganic salts from said detergent alkylate, the improvement comprising:

|(a) adding to said separated detergent alkylate portion, an effective amount of up to about 50 weight percent water based on the weight of said suspended catalyst sludge in said detergent alkylate portion containing trace amounts of suspended catalyst slulge, thereby coagulating and precipitating said suspended catalyst sludge, and

(b) separating said detergent alkylate from the coagulated and precipitated catalyst sludge.

2. The method of claim ll wherein said suspended slude is present in an Iamount in the range of about 0.1 to 0.7 Weight percent based on the total weight of the detergent alkylate.

3. The mehod of claim 1 wherein step (a) is carried out at a temperature within the range of about 20 C. to C.

4. The method of claim 3 wherein said temperature is within the range of about 25 C. to 60 C.

5. The method of claim 1 wherein said aluminum halide catalyst is selected from the group consisting of aluminum chloride and aluminum bromide.

6. The method of claim 1 wherein said Water is admixed with an aryl hydrocarbon carrier similar to said aryl hydrocarbon employed in the alkylation step for preparing detergent alkylates.

7. The method of claim 6 wherein said aryl hydrocarbon carrier is benzene.

References Cited UNITED STATES PATENTS 2,771,496 11/ 1956 Hervert 260--671 3,337,613 8/1967 Luberot 260-671 2,538,262 l/l951 Murray 26S-674 3,118,956 1/1964 Feighner et al. 260-671 3,316,294 4/ 1967 Feighner et al. 260-671 DELBERT E. GANTZ, Primary Examiner C. E. SPRESSER, IR., Assistant Examiner U.S. Cl. X.R. 208-413; 260-671 B 

